Experimental investigation on influence of loading rate on rockburst in deep circular tunnel under true-triaxial stress
- PDF / 6,456,824 Bytes
- 16 Pages / 595.22 x 842 pts (A4) Page_size
- 41 Downloads / 215 Views
Experimental investigation on influence of loading rate on rockburst in deep circular tunnel under true-triaxial stress condition SI Xue-feng(司雪峰)1, HUANG Lin-qi(黄麟淇)1, GONG Feng-qiang(宫凤强)2, LIU Xi-ling(刘希灵)1, LI Xi-bing(李夕兵)1 1. School of Resources and Safety Engineering, Central South University, Changsha 410083, China; 2. School of Civil Engineering, Southeast University, Nanjing 211189, China © Central South University Press and Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract: To investigate the influence of loading rate on rockburst in a circular tunnel under three-dimensional stress conditions, the true-triaxial tests were conducted on 100 mm×100 mm×100 mm cubic sandstone specimens with d50 mm circular perforated holes, and the failure process of hole sidewall was monitored and recorded in real-time by the microcamera. The loading rates were 0.02, 0.10, and 0.50 MPa/s. The test results show that the rockburst process of hole sidewall experienced calm period, pellet ejection period, rock fragment exfoliation period and finally formed the V-shaped notch. The rockburst has a time lag and vertical stress is high when the rockburst occurs. The vertical stress at the initial failure of the hole sidewall increases with loading rate. During the same period after initial failure, the rockburst severity of hole sidewalls increased significantly with increasing loading rate. When the vertical stress is constant and maintains a high stress level, the rockburst of hole sidewall under low loading rate is more serious than that under high loading rate. With increasing loading rate, the quality of rock fragments produced by the rockburst decreases, and the fractal dimension of rock fragments increases. Key words: rockburst; loading rate; deep circular tunnel; true-triaxial test; V-shaped notch Cite this article as: SI Xue-feng, HUANG Lin-qi, GONG Feng-qiang, LIU Xi-ling, LI Xi-bing. Experimental investigation on influence of loading rate on rockburst in deep circular tunnel under true-triaxial stress condition [J]. Journal of Central South University, 2020, 27(10): 2914−2929. DOI: https://doi.org/10.1007/s11771-020-4518-4.
1 Introduction In deep underground engineering, rockburst is a dynamic failure phenomenon under high geostress conditions [1−6], which has a serious threat to construction personnel and equipment [7−15]. The occurrence of rockburst disasters is closely related to the high geostress, excavation unloading, and stress adjustment caused by dynamic disturbances in deep hard rocks [16]. However, there is no obvious precursor before the rockburst and it is sudden. There is great difficulty in monitoring and
predicting rockbursts in actual engineering. To clarify the process of rockburst occurrence and the mechanism of rockburst induction, a multitude of experimental studies have been conducted. Under one-dimensional loading conditions, SALAMON [17] analyzed the relationship between specimen force and deformation, and discussed the stability of pillar workings, and introduced a design criterio
Data Loading...
